| The physical chemistry properties of ozone and its application in water treatment are reviewed, and the emphasis of discussion is put on zeolite catalytic ozonation technology developed recently. On the basis of present research situation of ozonation, the research task of this work was proposed. The content of dissertation mainly includes three parts: degradation of acetic acid by O3, H2O2/O3, TS-1/O3, TS-1/H2O2/O3 at different pH values(3, 7, 10); The mechanism of oxidation of acetic acid by TS-1/H2O2/O3 TS-1/H2O2/O3 at the initial pH of 3; degradation of acetic acid by different Si/Ti ratios TS-1/H2O2/O3The efficiencies of O3, H2O2/O3, TS-1/O3, TS-1/H2O2/O3 for acetic acid degradation were compared at initial pH values of 3, 7, 10. The result showed that H2O2/O3 had best oxidation efficiency at initial pH of 7, 10, and TS-1/H2O2/O3 had best oxidation efficiency at initial pH of 3. The paramenters’ optimization indicated that TS-1 probably led to invalid decomposition of some H2O2 in neutal and alkaline solution, thus decreasing the oxdative efficiency of TS-1/H2O2/O3. The result showed that TS-1/H2O2/O3 was suitable for treatment of acid wastewater, which might provide a complement way to H2O2/O3.The oxidative efficiency of H2O2/O3 in the presence or absence of titanium silicalite of TS-1 was investigated at initial pH value of 3.0, in which acetic acid was selected as the target organic compound owing to its inert to ozone. The removal rate of acetic acid by H2O2/O3 was negligible(5.6% in 30 min) because of the impossible deprotonation reaction of H2O2 in acidic solution. However, addition of titanium silicalite of TS-1 could greatly improve the oxidative efficiency of H2O2/O3(29% in 30 min). Effects of different parameters such as concentration of H2O2, concentration of TS-1, rate of ozone input, and pH value, on the oxidative efficiency of TS-1/H2O2/O3 showed that the degradation of HAc by TS-1/H2O2/O3 might be controlled by the transfers of reactants(including ozone and HAc) to the surface of TS-1. The tests of addition of tert-butyl alcohol and dimethyl sulfoxide(DMSO) both confirmed generation of hydroxyl radicals in this process. The rate of generation of hydroxyl radicals could be controlled by adjusting the concentration of H2O2. The mechanism for generation of hydroxyl radicals might be the reaction of some reactive oxygen species(including Ti(IV)-superoxide and Ti(IV)-hydroperoxide/peroxide) which resulted from the interaction of TS-1 with H2O2, with dissolved ozone. The results are of significance for the effective pretreatment of acidic wastewater containing refractory ozone-inert organic matter.Oxalic acid was degraded by ozonation alone and different Si/Ti ratios TS-1 catalytic ozonation at initial pH value of 3. The result showed that the presence of TS-1 catalyst at different ratios of Si/Ti 35:1, 70:1, 140:1(named TS-1-35, TS-1-70, TS-1-140) improved the ozonation efficiency and removal rate of oxalic acid were 11.4%, 7.4%, 5.3%, respectively, which were higher than the sum of ozonation alone 1.4% and adsorption by TS-1 0.5%. The lower Si/Ti ratio TS-1 had higher catalytical efficiency, which might be related to amount of the activity center Ti in TS-1. When adding 10 ppm concentration of H2O2 to the solution, the removal rates of oxalic acid were enhanced to 76.8%, 70.8%, 68.5%, respectively. The lower Si/Ti ratio TS-1 still had higher catalytical efficeincy. Furthermore, increase of concentration of H2O2 improved the degradation rate.When adding tert-butyl alcohol to the solution, the removal rate of oxalic acid by TS-1/H2O2/O3 and TS-1/O3 fell to 1.8% and 1.5%. The result indicated that two oxidation process generated ·OH. on the basis of the experimental data, the ratio of four pathways of degradation oxalic acid was quantified. |
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